Einwenden könnte man, durch die ‹alles zermalmende› Kritik (Mendelssohn 1785, «Vorbericht») werde die Metaphysik nicht grundlegend verändert, sondern recht eigentlich abgeschafft.
(Otfried Höffe, Kants Kritik der reinen Vernunft, p. 18)
I'm not sure I understand the beginning of this sentence, the "einwenden könnte man" part of it. Translated literally, it should mean, One could oppose, or, One could object, but it feels incomplete, as if a direct object, like es, is missing.
What, then, is the correct translation of these words, which rather seem to form an idiom?